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Help please1980 Johnson 70 hp

R

rick_sr

New member
"Motor was making a noise in t

"Motor was making a noise in the power head or just below. Sounds like a rattle, still runs but now has bad vibration. Where can I start to see what may be the matter??
Thanks,
Rcik"
 
"Rick, First off, do not run t

"Rick, First off, do not run the engine.

Check for free-play in the rod bearings.
I assume you haven't any kind of dial indicator so, remove the spark plugs then insert a pencil or something like that in to the cylinder. Move the crankshaft back and forth just enough to feel the point that the piston starts to move. Take note if one cylinder has more movement of the crankshaft before the piston begins to move than others do. If so, it is time for a tear down and inspection. Sorry.
It kind of sounds like a failing bearing, but then again it could be something entirely different. These motors were very well build. If run with the correct oil fuel mix at the correct rpm, the failure of bearings is rare at best."
 
"Guest, Thank you
I do have a

"Guest, Thank you
I do have a Incicator, I will check for any free-play and get back with you. The noise started out like maybe it was in the very top of the engine under the flywheel. While running wot it had a power drop and when it came back to wot is when the noise got really bad and the vibration started. Almost felt like something was wrapped around the prop."
 
"Well I did the pencil in the

"Well I did the pencil in the cylinders and the bottom one is bad. The rod is broke or it pulled out of the piston. Is this motor worth a complete overhaul?? I have rebuild many car motors and when you break a rod it usually destroyes the crank, will this be the case with this motor?? Thanks for the help, you guys are great.
Rick"
 
"I am just finishing the rebui

"I am just finishing the rebuild of my 1977 70HP. Number one piston & ring let go - it was still running though. It depends upon how well you know your engine (ie it has usually run well), and how much another will cost and if you can do it your self. All parts are still available. Biggest cost will be the crank (mine had scoring on the main journals). You can get these new on ebay US$400. I acutally bought a non-running 77 70HP very cheaply through ebay and have sourced a good crank rod etc. Good luck"
 
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